Clean table/types if exist before running test

test/duckdb_test/column_test.rb

@@ -83,6 +83,10 @@ def test_name
     def create_data
       @@db ||= DuckDB::Database.open # FIXME
       con = @@db.connect
+
+      con.query(drop_table_sql)
+      con.query(drop_type_enum_sql)
+
       con.query(create_type_enum_sql)
       con.query(create_table_sql)
       con.query(insert_sql)
@@ -95,7 +99,7 @@ def create_type_enum_sql
 
     def create_table_sql
       sql = <<-SQL
-        CREATE TABLE table1(
+        CREATE TABLE IF NOT EXISTS table1(
           boolean_col BOOLEAN,
           tinyint_col TINYINT,
           smallint_col SMALLINT,
@@ -161,5 +165,13 @@ def insert_sql
       sql += ')'
       sql
     end
+
+    def drop_type_enum_sql
+      "DROP TYPE IF EXISTS mood;"
+    end
+
+    def drop_table_sql
+      "DROP TABLE IF EXISTS table1;"
+    end
   end
 end